Content boundary signaling techniques

ABSTRACT

Methods and devices provide a user interface that provides visual cues when a document pan or scroll has reached an end or boundary by distorting the document image in response to further user inputs. The image distortion functionality may include shrinking, stretching, accordion expansion, or bouncing of a document image. The degree of image distortion may be proportional to the distance that a user input would have the document move beyond the encountered boundary. When a boundary of a document image is reached during a rapid pan or scroll, a bouncing image distortion may be applied to the document image to inform the user that the document reached a boundary during the movement.

The present application is a continuation of U.S. patent applicationSer. No. 12/580,956, filed Oct. 16, 2009, entitled “Content BoundarySignaling Techniques,” which is hereby incorporated by reference in itsentirety.

FIELD OF THE INVENTION

1. Field of the Invention

The present invention relates generally to computer user interfacesystems and more particularly to user systems providing image distortionfunctionality.

2. Background

Personal computing devices (e.g. cell phones, PDAs, laptops, gamingdevices) provide users with increasing functionality and data storage.Personal computing devices serve as personal organizers, storage fordocuments, photographs, videos, and music, as well as portals to theInternet and electronic mail. In order to fit within the small displaysof such devices, large documents (e.g., photographs, music files andcontact lists) are typically displayed in a viewer that can present aportion of the document in a size large enough to be read and becontrolled by scrolling or panning functions to reveal other portions.In order to view all or parts of a document image or sort through a listof digital files, typical graphical user interfaces permit users to usescroll or panning functions by making unidirectional movements of onefinger on a touchscreen display, as implemented on mobile devices suchas the Blackberry Storm®. However, because of the small size of theviewer in portable computing devices, the entire contents of documentimages do not generally fit in the display. Since only a portion of alarge document is generally displayed in the viewer of a computingdevice, users may lose their position and orientation with respect tothe entire document. As such, users may be unable to appreciate theboundaries of a document image based on the portion of a document imagethat is displayed on the viewer.

SUMMARY

The various aspects include methods for implementing a user interfacefunction on a computing device, including detecting an input of adocument movement gesture on a user interface device (e.g., a touchevent on a touch surface) of the computing device, determining adocument image movement of a document displayed on the computing devicebased on the movement gesture input, determining whether a boundary ofthe document is reached based on the determined movement of the documentimage, and distorting an image of the document displayed on thecomputing device when a boundary of the document image is reached.Distorting the image of the document may involve one of stretching thedocument image, shrinking the document image, and bouncing the documentimage. Distorting the image of the document may include distorting thedocument image along an axis selected from a horizontal axis, a verticalaxis, a diagonal axis, and both the horizontal and vertical axes.Distorting the image of the document image may include distorting thedocument image in an accordion style by inserting space between displayimage elements without distorting the display image elements. The aspectmethods may be implemented on a computing device in which the userinterface device is a touch surface, and the document image movementgesture input is a touch event detected on the touch surface. The aspectmethods may be implemented on a computing device in which the userinterface device is a touch surface, and the document image movementgesture input is a touch event detected on a touchscreen display.Distorting the image of the document image may include distorting thedocument image based on a distance that the touch event travels afterthe boundary of the document is reached. In a further aspect, themethods may further include initiating a rapid pan or scroll animationif the user input represents a flick gesture, determining whether an endof the rapid pan or scroll animation has been reached, and animating thedistortion of the document image if the boundary of the document imageis reached before the end of the rapid pan or scroll animation isreached. Such animating of the distortion of the document image mayinclude animating a bouncing movement of the document image, oranimating a bouncing movement and a compression distortion of thedocument image. In a further aspect, the methods may further includedetermining a distortion function to be applied to distort the documentimage, and calculating a distortion factor based on a distance thedocument image movement gesture input would move the document imagetouch event travels after the boundary is reached, in which distortingthe document image includes applying the determined distortion functionto the display image based on the calculated distortion factor. Thisaspect may further include determining whether a maximum level ofdisplay image distortion is reached, and reverting the display imageback to its original form if the maximum level of display imagedistortion is reached.

Another aspect is a computing device that includes a processor, adisplay coupled to the processor, and a user interface device (e.g., atouch surface, touch screen, computer mouse, trackball, etc.) coupled tothe processor, in which the processor is configured withprocessor-executable instructions to perform operations of the variousaspect methods.

Another aspect is a computing device that includes means foraccomplishing the functions involved in the operations of the variousaspect methods.

Another aspect is a computer readable storage medium having storedthereon computer-executable instructions configured to cause a computerto perform the processes of the various aspect methods.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated herein and constitutepart of this specification, illustrate exemplary aspects of theinvention. Together with the general description given above and thedetailed description given below, the drawings serve to explain featuresof the invention.

FIG. 1A is a frontal view of a portable computing device showing a listdocument on a touchscreen display.

FIG. 1B is a frontal view of a portable computing device illustrating alist end distortion functionality activated by a finger moving in an updirection on a touchscreen display according to an aspect.

FIGS. 2A and 2B are frontal views of a portable computing deviceillustrating a distortion functionality activated by a finger moving inan up direction on a touchscreen display according to another aspect.

FIG. 3 is a process flow diagram of an aspect method for applying adistortion function to the display image.

FIG. 4 is a process flow diagram of an aspect method for applying abounce distortion function to the display image.

FIG. 5 is a component block diagram of an example mobile computingdevice suitable for use with the various aspects.

FIG. 6 is a component block diagram of an example portable computingdevice suitable for use with the various aspects.

DETAILED DESCRIPTION

The various aspects will be described in detail with reference to theaccompanying drawings. Wherever possible, the same reference numberswill be used throughout the drawings to refer to the same or like parts.References made to particular examples and implementations are forillustrative purposes and are not intended to limit the scope of theinvention or the claims.

The word “exemplary” is used herein to mean “serving as an example,instance, or illustration.” Any implementation described herein as“exemplary” is not necessarily to be construed as preferred oradvantageous over other implementations.

As used herein, the terms “personal electronic device,” “computingdevice” and “portable computing device” refer to any one or all ofcellular telephones, personal data assistants (PDAs), palm-topcomputers, notebook computers, personal computers, wireless electronicmail receivers and cellular telephone receivers (e.g., the Blackberry®and Treo® devices), multimedia Internet enabled cellular telephones(e.g., the Blackberry Storm®), and similar electronic devices thatinclude a programmable processor, memory, and a connected or integraltouch surface or other pointing device (e.g., a computer mouse). In anexample aspect used to illustrate various aspects of the presentinvention, the computing device is a cellular telephone including anintegral touchscreen display. However, this aspect is present merely asone example implementation of the various aspects, and as such is notintended to exclude other possible implementations of the subject matterrecited in the claims.

As used herein, a “touchscreen” is a touch sensing input device or atouch sensitive input device with an associated image display. As usedherein, a “touchpad” is a touch sensing input device without anassociated image display. A touchpad, for example, can be implemented onany surface of a computing device outside the image display area.Touchscreens and touchpads are generically referred to herein as a“touch surface.” Touch surfaces may be integral parts of a computingdevice, such as a touchscreen display, or a separate module, such as atouchpad, which can be coupled to the computing device by a wired orwireless data link. The terms touchscreen, touchpad and touch surfacemay be used interchangeably hereinafter.

As used herein, a “touch event” refers to a detected user input on atouch surface that may include information regarding location orrelative location of the touch. For example, on a touchscreen ortouchpad user interface device, a touch event refers to the detection ofa user touching the device and may include information regarding thelocation on the device being touched.

As used herein, “document” or “digital document” refers to any of avariety of digital content in which at least a portion can be displayedas a document image on a display of a computing device. Examples ofdigital documents encompassed in the term “document” include, but arenot limited to, digital photograph files (e.g., .tif, .JPG), documentfiles (e.g., .pdf, .txt, etc.), word processing files (e.g., .doc, .rtf,etc.), graphics and drawing files (e.g., .vsd) spread sheet files (e.g.,.xls), database files (e.g., .xml, .sql, etc.), contacts databases(e.g., address book application files maintained on cellulartelephones), file listings, music library listings, and similar digitallists. Thus, the reference to “document” is not intended to limit claimscope to a written document, but encompass all forms of digitalinformation that can be displayed consistent with the various aspects.

As used herein, “document image” refers to the image that a computingdevice may generate based on the document contents for presentation onthe display of the computing device. Examples of document imagesinclude, but are not limited to, digital photographs, displayed portionsof a text or word processing document (i.e., excluding metadata andformatting data), displayed graphics and widgets presenting informationcontained in a database or list file, extended menu lists (e.g., a musiclisting), and the display generated from spread sheet files.

As used herein, “document boundary” refers to any end, edge or boundarywithin the document beyond which a document image cannot extend.Examples of document boundaries include, but are not limited to, thebeginning of a list, database, or text document, the end of a list,database, or text document, each edge of a digital photograph, and thefirst and last entry in a database record.

Since an image of the entire contents of a document, such as a wordprocessing document, picture image or a list of contacts, may notentirely fit in a touchscreen display of a computing device, mostgraphical user interfaces provide scrolling and panning functionality toenable the document image to be moved within the device view window. Toallow users to move document images within a touchscreen display, acomputing device may be configured to detect the tracing of touchgestures on the display and to move the document image with respect tothe view window in response to the direction of the touch gestures.Typical document control gestures enabled on touchscreen computingdevices include drag, pan, scroll, and “flick” gestures. In drag, pan,and scroll gestures, the user touches the touchscreen and moves thetouching finger in the desired direction of movement without raising thefinger. For example, to view the entire content of a contact list, thecontent of which does not fit in a computing device touchscreen displayframe, a user may trace a scroll gesture on the touchscreen to scrolldown the list of contacts. The scrolling function allows a user to bringinto the computing device display frame different parts of the contentlist and display it one portion at a time. In a flick gesture, the usertouches a touch surface (e.g., a touchscreen), rapidly moves a fingerup/down or left/right on the touchscreen and removes the finger in thesame motion as if to flick the content in a particular direction. Itshould be appreciated that a flick gesture (or a user input equivalentto a flick gesture) may also be accomplished on other types of userinput devices, such as by rapidly spinning a scroll wheel on a computermouse or a rapid spin of a trackball. Thus, the reference to a flickgesture is not necessarily limited to a flick gesture executed on atouch surface (e.g., a touchscreen).

Unlike standard personal computers, which trace the movement andboundaries of a document image by showing a display indicator such as ascrollbar on the computer display, many portable computing devicedisplays do not include such display indicators. The absence of displayindicators in portable computing device viewers frees valuable display“real estate” on which more of a display image may be shown. However, aportable computing device user who is trying to navigate through a largedocument (e.g., a long contact list) will often be unaware of theboundaries of the document (e.g., the top or the end of a list). Forexample, when scrolling down a list of emails by tracing a series ofscroll gestures on the touchscreen display, a user may not be able todiscern where the list begins or ends. When a user reaches the end ofthe email list not knowing that an end boundary is reached, the user maycontinue to trace scroll gestures in an attempt to continue scrollingthrough the list. When the list fails to respond to the scroll gesturesbecause the end of the list has been reached, the user may wonderwhether the computing device has frozen. The only way to confirm thatthe computing device is operating properly is to scroll in the otherdirection, which is an unnecessary motion. Such ambiguous operation atthe end of a list or boundary of document may cause user frustration andconfusion.

The various aspect methods provide a user interface image distortionfunctionality which provides a visual cue or signal to inform computingdevice users when drag, pan, scroll, and flick gestures would move adocument beyond the document's boundaries. This visual cue includes anintuitive distortion of the image as though the user's gesture weredistorting a physical document. The computing device may be configuredto detect when a document boundary is reached and a user gestureattempts to move the document beyond the boundary, and to distort thedisplay image consistent with the user gesture. For example, when a userreaches the end of an email list while tracing a scroll gesture on atouchscreen display, the computing device may distort the displayedimage of the last email items as if the list were a plastic sheet or anaccordion stack of linked items. Thus, the various aspect methodsprovide an intuitive signal to users when their drag, pan, scroll, andflick gestures have reached a document boundary without having todisplay scroll bar indicators which occupy valuable display “realestate.”

While the various aspects are described with reference examplesimplemented on computing devices equipped with touchscreen displays, theaspects and the claims are not limited to such implementations. Thevarious aspects may be implemented in any computing device displayingdocument images that extend beyond the edges of the display window andreceive user inputs from user input devices (e.g., a touch surface,computer mouse, track ball, etc.) for moving the document image withrespect to the display window. The various aspects provide intuitivevisual cues sufficient to obviate the need for scroll bar indicators,thereby increasing the display real estate available for displaying thedocument image. For example, a document image movement gesture, such asa drag, pan, scroll or flick may also be accomplished using aconventional computer mouse or track ball as is well known. Thus, theexamples of executing drag, pan, scroll and flick gestures on atouchscreen user interface device refer to a particularly advantageousimplementation of the aspects and are not intended to limit the scope ofthe claims to touchscreen user interface devices.

In the various aspects, the image distortion functionality may beenabled as part of the graphical user interface (GUI) functionality oras part of an application (e.g., a contact list or photo viewerapplication). Automatic activation of the image distortion functionalitywithin the GUI may be provided as part of an application. Also, theimage distortion functionality may be provided as a default functionwithin a GUI or application.

In some aspects, the image distortion functionality may be manuallyenabled. A user may select and enable/activate the image distortionfunctionality manually by pressing a button or by activating an icon ona GUI display. For example, activation of the functionality may beassigned to a soft key, which the user may activate (e.g., by pressingor clicking) to launch the image distortion functionality. As anotherexample, the image distortion functionality may be activated by a usercommand. For example, the user may use a voice command such as “activatelist end signal” to enable the image distortion functionality. Onceactivated, the image distortion functionality may be used in the mannerdescribed herein.

The image distortion functionality may respond to any form of user touchgesture implemented on the computing device touch surface. Sincetouchscreens are generally superimposed on a display image, in aparticularly useful implementation the touch surface is a touchscreendisplay, thus enabling users to interact with the display image with thetouch of a finger. In such applications, the user interacts with animage by touching the touchscreen display with a finger and tracing backand forth or up and down paths.

The various aspects may distort a display image using different types ofdistortion, such as by shrinking, stretching or bouncing the image. Forexample, the computing device may distort the display image by uniformlystretching the content (referred to as a “flat stretch”), bylogarithmically stretching portion of the content (i.e., referred to asa “partial stretch”), by stretching a portion of the image along onedirection while shrinking a portion of the image along the perpendiculardimension (referred to as a “local stretch”), or by creating empty spacebetween fixed size items (referred to as an “accordion stretch”).

FIGS. 1A and 1B illustrate a list end distortion functionality in whicha uniform or flat stretch distortion is applied to a list document toinform a user that the end of a contacts list has been reached. Asillustrated in FIG. 1A, a user may scroll through a list of contacts bytracing a finger 108 on the touchscreen surface 104 as shown by thedotted arrow 106. The dotted arrow 106 is shown here only to illustratethe direction of the traced gesture. Since the display 102 of thecomputing device 100 does not include a display indicator to allow theuser to determine the boundaries of the contacts list, the user may haveno way to know when the end of the list has been reached.

As illustrated in FIG. 1B, the computing device 100 may be configured toinform the user that the end of the list is reached by distorting thedisplay image in response to further scroll (or other) user gestures. Inthe illustrated example the computing device 100 is configured to applya uniform distortion to the display that uniformly stretches the displayimage along the direction of the scroll gesture as though the user isstretching an elastic material on which contact information is printed.Such visual distortion of the contacts list intuitively informs the userthat the end of the list is reached and that the computing device isworking properly even though the list is not scrolling further.

To apply a uniform or flat stretching distortion, the computing device100 may scale the display image uniformly. As such, uniform or flatstretching distortion factors may be applied to the display image alongthe direction of the user touch gestures. As illustrated in FIG. 1B, auser input gesture that attempts to move or scroll the document imagebeyond the document's end or boundary may stretch the document along thedirection of the scroll. Other forms of distortion may also be applied.For example, a user input gesture that attempts to move or scroll beyonda document boundary may cause a stretch along the axis of the user touchgesture and a pinch or shrinkage along the perpendicular direction asmight occur to an elastic fabric. In a further aspect, the distortionmay be applied in an opposite direction such that if the user inputgesture attempts to move the document image in a horizontal direction onthe touchscreen display, the image is stretch along its vertical axis(i.e., its height), and if the user attempts to move the document in avertical direction on the touchscreen display, the image may be stretchalong its horizontal axis (i.e., its width). In a further aspect, if theuser input gesture attempts to move the document in a diagonal scrollgesture (e.g., towards the corners of the touchscreen display), theimage may be stretched along both the horizontal and vertical axesproportional to the angle of the traced touch gesture.

In an aspect, the degree to which a display image is stretched isdetermined by a distortion factor that is calculated based upon themovement that would be imparted to the document image beyond theencountered boundary by the user's input gesture, such as a touchgesture on a touchscreen. The computing device 100 may be configured tocalculate the distortion factor based on the distance that the userinput gesture (e.g., touch event) would have the document move once aboundary is reached. For example, in FIG. 1B, the computer device 100may detect the end of the contacts list and stretch the contact listbased on the distance the user's finger 108 moves on the touchscreen 104once the end of the contact list is reached. The farther the user'sfinger 108 moves on the touchscreen 104, the greater the distortionfactor, and the more the contact list image is distorted. When the userterminates the touch event the stretched display image automaticallyreverts back to its original form.

The distortion factor may be applied to distort the display imageproportionately. For example, when applying a stretch effect to thedisplay image, the computing device 100 may be configured to distort adisplay image proportional to the distance that the document imagemovement gesture input would move the document image beyond the documentboundary, such as the distance the touch event travels on thetouchscreen 104 after the document boundary is reached. Thus, the longerthe distance traveled by the touch event, the more severe the distortionof the display image.

In an aspect, the computing device 100 may be configured to limit theextent to which a display image may be distorted. Once the display imagereaches its maximum distorted shape, no further distortion may beapplied. A stretched display image may also automatically revert back toits original form when the user terminates the touch event.

The automatic reversion of display images back to their original shapemay occur in different ways. For example, the automatic reversion may bean animated reversal of the distortion, or an animated under-damping. Inan animated reversal the computing device 100 may be configured toanimate the reversion of the image back to its original shape, as ifundoing the stretching.

The animated under-damping effect reflects the behavior of elasticsystems. In nature, when elastic systems are released from tension theyoften do not stop upon reaching their original shapes, and insteadcontinue bounce back and forth about the original shape before settlinginto their original states. For example, when an elastic band isstretched and released, the band moves towards its resting state butdoes not immediately find its original shape. As the band releasespotential energy, the band may first shrink and stretch again forcertain number of times before it is back to its original form. Thecomputing device 100 may be configured to animate the image distortiontransition so as to mimic such natural effects in order to provide theuser with a perception of interacting with real world objects.

As mentioned above, one type of image distortion that may be applied invarious aspects is an accordion stretch which inserts space betweenimage elements without changing the shapes of the elements themselves.This aspect is illustrated in FIGS. 2A and 2B. The accordion stretchdistortion creates the appearance of stretching material that liesbetween the content elements (e.g., graphical widgets) of a documentimage. The appearance of stretchy “goo,” cords, or rubber materialbetween fixed size image elements may provide the appearance ofstretching the whole image without distorting the actual contents of theimage.

FIG. 2A illustrates a contacts list being browsed by a user tracingscroll gestures with a finger 108. The user may move the contacts listupwards by touching the touchscreen surface 104 of a computing device100 using a finger 108, and tracing an upward scroll gesture along thedotted arrow 106. Similar to the computing device 100 shown in FIGS. 1Aand 1B, the display 102 does not include a scroll bar indicator toinform the user about the boundaries of the contacts list. Therefore,the user may not know when the end of the list is reached.

FIG. 2B the accordion stretch image distortion behavior of the displaywhen the bottom end of the contacts list is reached. FIG. 2B illustrateshow the accordion stretch distortion does not change the shape of thecontact list display elements (i.e., the contact names, pictures andphone numbers). Instead, the image appears to stretch the goo 112 thatlies between the contact data display elements.

Other stretch effects may also be applied in the same manner describedabove with respect to FIGS. 1A, 1B, 2A, and 2B. In an aspect, acomputing device 100 may be configured to apply partial stretchingeffects to the display image, such that when a boundary of a documentimage is reached, only certain portions of the display image arestretched while the remainder is unchanged. For example, the portion ofthe display image that is stretched may be the portion that is betweenthe touch location of the finger 108 and the reached boundary of thedocument image.

In a further aspect, the display image may appear to be stretched usinga local/logarithmic stretch method. In this style of stretching, thedisplay image may appear stretched in a logarithmic fashion to allow theportion being stretched to smoothly transition into the portion of thedocument image that does not appear stretched.

In a further aspect, the display image may be distorted by locallycompressing its content. This distortion style may be applied, forexample, when the entire document image fits within the display frame.As a user attempts to move the document image to one direction, the sideof the document image in the direction of the movement may appearcompressed while the other opposite side of the document image mayappear stretched. For example, the entire list of contacts may fitwithin the display 102 of a computing device 100. If a user attempts tomove the contact list downwards by tracing a downward scroll gesture onthe touchscreen surface 104, the content of the contact list locatedbelow the touch location of the finger 108 may be compressed while thecontents above the finger 108 may be stretched.

In a further aspect, when a document boundary is reached during a rapidscroll, such as may occur following a flick gesture, the image may bedistorted in a bounce effect to inform a user that a document imageboundary has been reached. A rapid scroll typically occurs when a usertraces a quick gesture to rapidly move through the contents of adocument (e.g., a list) or pan a large image using fewer scrollgestures. Generally, the length of the scroll will depend on the speedand/or distance of the flick gesture. For example, a computing device100 may be configured to determine the speed of a flick gesture tracedon a touchscreen surface 104, and based on the determined speedcalculate an endpoint for the scroll or pan, such as a number of listelements that should be scroll or pixels that an image should move withrespect to the display view window. A fast scroll gesture may result inthe end of a list or the boundary of an image been reached before thecalculated endpoint is reached. To inform the user that the flickgesture has reached the end of a list or a boundary of the document, thecomputing device 100 may be configured to bounce the image within thedisplay to inform the user that the boundary was reached. In a bounceeffect, the displayed image may appear to reach a limit in onedirection, reversed direction a small amount and then reversed directionagain before settling on the end of the document (e.g., displaying thelast item in the list or the portion of an image encompassing theencountered a boundary).

In the bounce effect, the computing device 100 may also apply thestretch or shrink effects described above with respect to FIGS. 1A, 1B,2A, and 2B. For instance, once a boundary of a document image is reachedduring a rapid scroll and a bounce effect is applied, a stretch effectmay also be applied in the direction of the movement of the documentimage. Thus, if the document image is moving downwards with respect tothe display, when the bottom boundary is reached, the document image maycompress like a ball striking the floor, rebound a small distance, andrevert back to its original shape (i.e., simulating a bounce effect)before coming to a resting state. In other aspects, shrink effects and acombination of stretch and shrink effects may also be used to simulatebouncing effects. The number of rebounds and stretch cycles may beconfigured by an application developer to achieve a desired userexperience.

In a typical computing device, a processor may receive touch eventupdates from a touchscreen (or other type of touch surface)periodically, such as every few milliseconds. When a user touches thetouchscreen, the processor may receive a “touch down” event notificationin the next update from the touchscreen, and in each subsequent updatefrom the touchscreen receive a touch location notification until a“touch up” event notification is received. Since the touch locationinformation provided by the touchscreen occurs very frequently, amovement of a user's touch across the surface of the touchscreen will bedetected by the processor as a sequence of touch locations which changeover time.

FIG. 3 illustrates a process flow of an aspect method 300 for applying adistortion function to a displayed image in response to a scroll eventbeyond a document boundary. In method 300 at block 302, a computingdevice 100 may be configured to detect a touch event on a touch surfaceor user input on another form of user interface device (e.g., a computermouse or trackball), and determine whether a touch event was a touch upevent (or release of a computer mouse button) at determination block304. If a touch up event is detected (i.e., determination block304=“Yes”), the computing device 100 may terminate the distortionfunction at block 306. If the touch event was not a touch up event(i.e., determination block 304=“No”), the computing device 100 maydetermine the document image movement that should be caused to happenbased on the touch event (or other type of user interface input event)at block 308. This may be accomplished by comparing the current touchlocation (or other type of user interface input event) received at block302 to the previous touch location (or other type of user interfaceinput event) which may be stored in memory. If the touch location haschanged, this may indicate a drag, scroll, or flick gesture is beingimplemented to cause a movement in a displayed document (e.g., a scrollof a displayed list). At determination block 310, the computing device100 may determine whether a boundary of the displayed document image hasbeen reached. If a boundary of the document image and not in reached(i.e., determination block 310=“No”), the computing device 100 mayperform normal graphical user interface (GUI) function associated withthe determine document movement at block 312, and return to block 302 toreceive the next touchscreen touch location event (or other type of userinterface input event). For example, if a boundary of a document imageis not reached and the user is inputting a scroll down function, thecomputing device 100 may continue to scroll down the document image solong as the user's finger remains in contact with the touchscreen andcontinues to move.

Once a boundary of the document image is reached (i.e., determinationblock 310=“Yes”), the computing device 100 may determine a distortionthat should be applied to the displayed image and, if appropriate,calculate a distortion factor to be used in distorting the image. Theparticular distortion to be applied to the displayed image may dependupon the application, the nature of the document, user settings andother information. As discussed above, a variety of different distortionfunctions may be applied to documents according to the various aspects.Thus, an application developer may specify a particular distortionfunction for particular types of documents. Also, users may be allowedto select a particular distortion function as part of their usersettings. Thus, some users may prefer to have greater distortion appliedto images so that it is easier to determine when a list and or documentboundary has been reached, while some users may prefer to have little orno distortion applied. The amount of distortion to be applied may bedetermined by a distortion factor that may be calculated based on thedistance that the user input gesture (e.g., a touch event) would havethe document image move after a boundary of the document is reached, orthe distance that an input gesture (e.g., a touch event) would cause adocument to move beyond its boundary. Thus, the longer the touch event(or other type of user input), the greater the distortion that will beapplied to the image. At block 314, the computing device 100 may applythe determined distortion function to the display image in accordancewith the calculated distortion factor. For instance, if the end of acontact list is reached while the user is tracing an upward scrollgesture, the computing device 100 may apply a distortion function, suchas a stretching effect, to inform the user that the end of the documentimage is reached.

The computing device continues to detect touch events (or touch computermouse button presses, etc.) with each touchscreen update at block 302.Thus, the degree of image distortion applied to the displayed image willcontinue to depend upon the user input gesture, such as the location ofthe user's finger on the touchscreen. If the user scrolls backward(i.e., away from the document boundary) without lifting a finger fromthe touchscreen (or touch surface, computer mouse, etc.), the amount ofdistortion applied to the displayed image at block 314 will be reduced.If the user lifts a finger off of the touchscreen (or touch surface,computer mouse, etc.), a touch up event will be detected at block 302,which will be determined at determination block 304, prompting an end ofthe distortion function at block 306. Terminating the distortionfunction will allow the displayed image to return to normal. In anaspect, terminating the distortion function at block 306 may includeanimating the release of the distortion.

In an optional aspect, at optional determination block 316, thecomputing device 100 may be configured to determine when a maximumdistortion level of the document image is defined by the calculateddistortion factor and the determined distortion function. If the usercontinues a touch gesture (or other type of user interface input) afterthe image has been distorted a maximum amount, this may indicate thatthe user is actually executing a different type of GUI input (i.e., agesture other than a drag, scroll or flick gesture) for which imagedistortion is not appropriate. A maximum distortion level depend uponother types of GUI touch gestures (or other type of user interfaceinput) that may be executed and/or may be assigned to each documentimage to enable the computing device 100 to determine the extent towhich the document image may be distorted. For example, an email listmay have a maximum distortion level of 3 centimeter, so that once aboundary is reached, the computing device 100 may only distort thedisplayed email items based on the first 3 centimeter of a linear scrollgesture. If a touch event (or other type of user interface input) wouldcause more than the designated maximum distortion level, the computingdevice 100 may be configured to revert the image back to its originalform, as may be appropriate for another type of touch gesture. If themaximum distortion of the image is reached (i.e., optional determinationblock 316=“Yes”), the computing device 100 may revert the display imageto its original form at optional block 318 before receiving the nexttouch event at block 302. If a maximum distortion level is not reached(i.e., optional determination block 316=“No”), the computing device 100may continue the current level of distortion and receive the next touchevent at block 302.

FIG. 4 illustrates a process flow of another aspect method 400 forapplying a distortion function during a rapid scroll or pan, as mayoccur in response to a flick gesture. In method 400 at block 302, acomputing device 100 may detect a touch event and determine whether thetraced gesture is a flick gesture at determination block 404. If thegesture is not a flick gesture (i.e., determination block 404=“No”), thecomputing device 100 may proceed with the processing of method 300described above with reference to FIG. 3 by determine whether the touchevent (or other type of user interface input) was a touch up event atdetermination block 304 (FIG. 3). If the gesture is determined to be aflick gesture (i.e., determination block 404=“Yes”), the computingdevice 100 may determine how far the document will scroll or pan atblock 406. Methods for calculating the distance of a document movementor list scroll based upon a flick gesture are well known and may be usedin method 400.

The computing device may be configured to animate the movement of thedocument in response to the flick gesture, such as by panning thedocument beneath the display view window or rapidly scrolling through alist of elements. This animation may be accomplished by sequentiallydetermining the next display increment (e.g., the next item in the list)and generating a display including that increment until the rapid pan orscroll reaches a predicted end point. The determination of the nextdisplay increment may take into account deceleration factors so that thedisplay appears fast at first but slows over time until the end of therapid pan or scroll is reached. However, in a conventional computingdevice that does not include scroll bars in the display, a user may notbe aware of when a list end or document boundary has been reached.

To provide the user with a visual cue that the rapid document movementor scroll has encountered a document end or boundary, the computingdevice may test the document as it animates the movement. For example,at determination block 408, the computing device 100 may determinewhether the end of the rapid pan or scroll has been reached (i.e., thatthe document has come to the end of the travel indicated by the flickgesture). If the end of the pan or scroll has been reached (i.e.,determination block 408=“Yes”), the computing device 100 may continuenormal processing by detect the next touch event at block 302. If theend of the pan or scroll has not been reached (i.e., determination block408=“No”), this means that the animation should continue, so at block410 the computing device 100 may determine the next display increment.As mentioned above, the determination of the next display increment mayinclude determining a speed of the pan or scroll based upon factors suchas the speed imparted by the flick gesture and simulated friction whichimposes a deceleration effect in the animation. As the next displayincrement is determined, at determination block 414 the computing device100 may determine whether a boundary of the document is reached in thatdisplay increment. For instance, the computing device 100 may determinewhether the next display increment includes the end of an email list. Ifa boundary of the document has not been reached (i.e., determinationblock 414=“No”), the computing device 100 may generate a display showingthe next display increment at block 412, and return to block 408 toagain determine whether the end of the rapid pan or scroll has beenreached.

If a boundary of the document has been reached in the next displayincrement (i.e., determination block 414=“Yes”), the computing device100 may calculate a distortion factor to be applied to the display imagein a bounce distortion animation at block 313. The distortion factor maybe based on the speed of the rapid pan or scroll when the boundary isencountered. Thus, if the boundary is encountered immediately after arapid flick gesture when the document is animated as moving rapidly, thecalculated distortion factor may be greater, and thus the amount ofimage distortion (e.g., the degree of stretching or amount of bounce)may be more severe, than if the boundary is encountered towards the endof the rapid pan or scroll animation when the document appears to bemoving slowly. As mentioned above, the bounce distortion animation mayinclude one or more bounces and one or more cycles of image stretchingor compression. At block 416, the computing device 100 may apply abounce distortion animation to the display image in accordance with thecalculated distortion factor. Once the bounce animation has ended, thecomputing device may return to normal GUI function by receiving the nexttouch event at block 302.

As would be appreciated by one of skill in the art, the methods 300 and400 illustrated in FIGS. 3 and 4 represent examples of how the imagedistortion functions of the various aspects could be implemented in acomputing device. Any number of variations of the processes may beimplemented without departing from the scope of the claims.

The aspects described above may be implemented on any of a variety ofcomputing devices 100. Typically, such computing devices 100 will havein common the components illustrated in FIG. 5. For example, thecomputing devices 100 may include a processor 191 coupled to internalmemory 192 and a touch surface input device 104 or display 102. Thetouch surface input device 104 can be any type of touchscreen display101, such as a resistive-sensing touchscreen, capacitive-sensingtouchscreen, infrared sensing touchscreen, acoustic/piezoelectricsensing touchscreen, or the like. The various aspects are not limited toany particular type of touchscreen display 101 or touchpad technology.Additionally, the computing device 100 may have an antenna 194 forsending and receiving electromagnetic radiation that is connected to awireless data link and/or cellular telephone transceiver 195 coupled tothe processor 191. Computing devices 100 which do not include atouchscreen input device 104 (and thus typically do not have a display102) usually do include a key pad 196 or miniature keyboard, and menuselection keys or rocker switches 197, which serve as pointing devices.The processor 191 may further be connected to a wired network interface198, such as a universal serial bus (USB) or FireWire® connector socket,for connecting the processor 191 to an external touchpad or touchsurface on which the various aspects may also be applied.

In some implementations, a touch surface can be provided in areas of theelectronic device 100 outside of the touchscreen display 104 or display102. For example, the keypad 196 can include a touch surface with buriedcapacitive touch sensors. In other implementations, the keypad 196 maybe eliminated so the touchscreen display 104 provides the complete GUI.In yet further implementations, a touch surface may be an externaltouchpad that can be connected to the computing device 100 by means of acable to a cable connector 198, or by a wireless transceiver (e.g.,transceiver 195) coupled to the processor 191.

The aspects described above may also be implemented within a variety ofcomputing devices, such as a laptop computer 600 as illustrated in FIG.6. Many laptop computers include a touch pad touch surface that servesas the computer's pointing device, and thus may receive drag, scroll andflick gestures similar to those implemented on mobile devices equippedwith a touchscreen display. A laptop computer 600 will typically includea processor 601 coupled to volatile memory 602 and a large capacitynonvolatile memory, such as a disk drive 603. The computer 600 may alsoinclude a floppy disc drive 604 and a compact disc (CD) drive 605coupled to the processor 601. The computer device 600 may also include anumber of connector ports coupled to the processor 601 for establishingdata connections or receiving external memory devices, such as a USB orFireWire® connector sockets or other network connection circuits 606 forcoupling the processor 601 to a network. In a notebook configuration,the computer housing includes the touchpad 607, keyboard 608 and thedisplay 609 all coupled to the processor 601. Other configurations ofcomputing device may include a computer mouse or trackball coupled tothe processor (e.g., via a USB input) as are well known.

The computing device processor 191, 601 may be any programmablemicroprocessor, microcomputer or multiple processor chip or chips thatcan be configured by software instructions (applications) to perform avariety of functions, including the functions of the various aspectsdescribed above. In some portable computing devices 100, multipleprocessors 191 may be provided, such as one processor dedicated towireless communication functions and one processor dedicated to runningother applications. The processor may also be included as part of acommunication chipset.

The foregoing method descriptions and the process flow diagrams areprovided merely as illustrative examples and are not intended to requireor imply that the processes of the various aspects must be performed inthe order presented. As will be appreciated by one of skill in the artthe order of blocks and processes in the foregoing aspects may beperformed in any order. Words such as “thereafter,” “then,” “next,” etc.are not intended to limit the order of the processes; these words aresimply used to guide the reader through the description of the methods.Further, any reference to claim elements in the singular, for example,using the articles “a,” “an” or “the” is not to be construed as limitingthe element to the singular.

The various illustrative logical blocks, modules, circuits, andalgorithm processes described in connection with the aspects disclosedherein may be implemented as electronic hardware, computer software, orcombinations of both. To clearly illustrate this interchangeability ofhardware and software, various illustrative components, blocks, modules,circuits, and algorithms have been described above generally in terms oftheir functionality. Whether such functionality is implemented ashardware or software depends upon the particular application and designconstraints imposed on the overall system. Skilled artisans mayimplement the described functionality in varying ways for eachparticular application, but such implementation decisions should not beinterpreted as causing a departure from the scope of the presentinvention.

The hardware used to implement the various illustrative logics, logicalblocks, modules, and circuits described in connection with the aspectsdisclosed herein may be implemented or performed with a general purposeprocessor, a digital signal processor (DSP), an application specificintegrated circuit (ASIC), a field programmable gate array (FPGA) orother programmable logic device, discrete gate or transistor logic,discrete hardware components, or any combination thereof designed toperform the functions described herein. A general-purpose processor maybe a microprocessor, but, in the alternative, the processor may be anyconventional processor, controller, microcontroller, or state machine. Aprocessor may also be implemented as a combination of computing devices,e.g., a combination of a DSP and a microprocessor, a plurality ofmicroprocessors, one or more microprocessors in conjunction with a DSPcore, or any other such configuration. Alternatively, some processes ormethods may be performed by circuitry that is specific to a givenfunction.

In one or more exemplary aspects, the functions described may beimplemented in hardware, software, firmware, or any combination thereof.If implemented in software, the functions may be stored as one or moreinstructions or code on a non-transitory computer-readable medium. Theprocesses of a method or algorithm disclosed herein may be embodied in aprocessor-executable software module executed which may reside on anon-transitory computer-readable medium. Non-transitorycomputer-readable media includes both computer storage media andcommunication media including any non-transitory medium that facilitatestransfer of a computer program from one place to another. Anon-transitory storage media may be any available non-transitory mediathat may be accessed by a computer. By way of example, and notlimitation, such non-transitory computer-readable media may compriseRAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic diskstorage or other magnetic storage devices, or any other non-transitorymedium that may be used to carry or store desired program code in theform of instructions or data structures and that may be accessed by acomputer. Disk and disc, as used herein, includes compact disc (CD),laser disc, optical disc, digital versatile disc (DVD), floppy disk, andblu-ray disc where disks usually reproduce data magnetically, whilediscs reproduce data optically with lasers. Combinations of the aboveshould also be included within the scope of non-transitorycomputer-readable media. Additionally, the operations of a method oralgorithm may reside as one or any combination or set of codes and/orinstructions stored on a non-transitory machine readable medium and/ornon-transitory computer-readable medium, which may be incorporated intoa computer program product.

The foregoing description of the various aspects is provided to enableany person skilled in the art to make or use the present invention.Various modifications to these aspects will be readily apparent to thoseskilled in the art, and the generic principles defined herein may beapplied to other aspects without departing from the scope of theinvention. Thus, the present invention is not intended to be limited tothe aspects shown herein, and instead the claims should be accorded thewidest scope consistent with the principles and novel features disclosedherein.

What is claimed is:
 1. A method for implementing a user interfacefunction on a computing device, comprising: detecting an image movementgesture input on a user interface device of the computing device;determining an image movement of an image displayed on the computingdevice based on the detected image movement gesture input; determiningwhether a boundary of the image displayed on the computing device isreached based on the determined image movement; determining a distortionfunction to be applied to distort the image displayed on the computingdevice; calculating a distortion factor based on a distance the imagemovement gesture input would move the image displayed on the computingdevice after the boundary of the image displayed on the computing deviceis reached; and distorting the image displayed on the computing devicewhen a boundary of the image is reached by applying the determineddistortion function to the image displayed on the computing device basedon the calculated distortion factor.
 2. The method of claim 1, whereindistorting the image displayed on the computing device comprises one ofstretching the image displayed on the computing device, shrinking theimage displayed on the computing device, and bouncing the imagedisplayed on the computing device.
 3. The method of claim 1, whereindistorting the image displayed on the computing device includesdistorting the image displayed on the computing device along an axisselected from a horizontal axis, a vertical axis, a diagonal axis, andboth the horizontal and vertical axes.
 4. The method of claim 1, whereindistorting the image displayed on the computing device includesdistorting the image displayed on the computing device in an accordionstyle by inserting space between elements of the image displayed on thecomputing device without distorting the elements of the image displayedon the computing device.
 5. The method of claim 1, wherein: the userinterface device is a touch surface; and the image movement gestureinput is a touch event detected on the touch surface.
 6. The method ofclaim 5, wherein the touch surface is a touchscreen display.
 7. Themethod of claim 5, further comprising: initiating a rapid pan or scrollanimation if the touch event represents a flick gesture; determiningwhether an end of the rapid pan or scroll animation has been reached;and animating the distortion of the image displayed on the computingdevice if the boundary of the image displayed on the computing device isreached before the end of the rapid pan or scroll animation is reached.8. The method of claim 7, wherein animating the distortion of the imagedisplayed on the computing device comprises animating a bouncingmovement of the image displayed on the computing device.
 9. The methodof claim 7, wherein animating the distortion of the image displayed onthe computing device comprises animating a bouncing movement and acompression distortion of the image displayed on the computing device.10. The method of claim 1, further comprising: determining whether amaximum level of display image distortion is reached; and reverting theimage displayed on the computing device back to its original form if themaximum level of display image distortion is reached.
 11. A computingdevice, comprising: a processor; a display coupled to the processor; anda user interface device coupled to the processor; wherein the processoris configured with processor-executable instructions to performoperations comprising: detecting an image movement gesture input on theuser interface device of the computing device; determining an imagemovement of an image displayed on the display based on the detectedimage movement gesture input; determining whether a boundary of theimage displayed on the display is reached based on the determined imagemovement; determining a distortion function to be applied to distort theimage displayed on the display; calculating a distortion factor based ona distance the image movement gesture input would move the imagedisplayed on the display after the boundary of the image displayed onthe display is reached; and distorting the image displayed on thedisplay when a boundary of the image is reached by applying thedetermined distortion function to the image displayed on the displaybased on the calculated distortion factor.
 12. The computing device ofclaim 11, wherein the processor is configured with processor-executableinstructions such that distorting the image displayed on the displaycomprises one of stretching the image displayed on the display,shrinking the image displayed on the display, and bouncing the imagedisplayed on the display.
 13. The computing device of claim 11, whereinthe processor is configured with processor-executable instructions suchthat distorting the image displayed on the display includes distortingthe image displayed on the display along an axis selected from ahorizontal axis, a vertical axis, a diagonal axis, and both thehorizontal and vertical axes.
 14. The computing device of claim 11,wherein the processor is configured with processor-executableinstructions such that distorting the image displayed on the displayincludes distorting the image displayed on the display in an accordionstyle by inserting space between elements of the image displayed on thedisplay without distorting the elements of the image displayed on thedisplay.
 15. The computing device of claim 11, wherein the userinterface device is a touch surface, and wherein the processor isconfigured with processor-executable instructions such that the imagemovement gesture input is a touch event detected on the touch surface.16. The computing device of claim 15, wherein the touch surface is atouchscreen display.
 17. The computing device of claim 15, wherein theprocessor is configured with processor-executable instructions furthercomprising: initiating a rapid pan or scroll animation if the touchevent represents a flick gesture; determining whether an end of therapid pan or scroll animation has been reached; and animating thedistortion of the image displayed on the display if the boundary of theimage displayed on the display is reached before the end of the rapidpan or scroll animation is reached.
 18. The computing device of claim17, wherein the processor is configured with processor-executableinstructions such that animating the distortion of the image displayedon the display comprises animating a bouncing movement of the imagedisplayed on the display.
 19. The computing device of claim 17, whereinthe processor is configured with processor-executable instructions suchthat animating the distortion of the image displayed on the displaycomprises animating a bouncing movement and a compression distortion ofthe image displayed on the display.
 20. The computing device of claim11, wherein the processor is configured with processor-executableinstructions further comprising: determining whether a maximum level ofdisplay image distortion is reached; and reverting the image displayedon the display back to its original form if the maximum level of displayimage distortion is reached.
 21. A computing device, comprising: meansfor detecting an image movement gesture input on a user interface deviceof the computing device; means for determining an image movement of animage displayed on the computing device based on the detected imagemovement gesture input; means for determining whether a boundary of theimage displayed on the computing device is reached based on thedetermined image movement; means for determining a distortion functionto be applied to distort the image displayed on the computing device;means for calculating a distortion factor based on a distance the imagemovement gesture input would move the image displayed on the computingdevice after the boundary of the image displayed on the computing deviceis reached; and means for distorting the image displayed on thecomputing device when a boundary of the image is reached by applying thedetermined distortion function to the image displayed on the computingdevice based on the calculated distortion factor.
 22. The computingdevice of claim 21, wherein means for distorting the image displayed onthe computing device comprises one of means for stretching the imagedisplayed on the computing device, means for shrinking the imagedisplayed on the computing device, and means for bouncing the imagedisplayed on the computing device.
 23. The computing device of claim 21,wherein means for distorting the image displayed on the computing deviceincludes means for distorting the image displayed on the computingdevice along an axis selected from a horizontal axis, a vertical axis, adiagonal axis, and both the horizontal and vertical axes.
 24. Thecomputing device of claim 21, wherein means for distorting the imagedisplayed on the computing device includes means for distorting theimage displayed on the computing device in an accordion style byinserting space between elements of the image displayed on the computingdevice without distorting the elements of the image displayed on thecomputing device.
 25. The computing device of claim 21, wherein: theuser interface device is a touch surface; and the image movement gestureinput is a touch event detected on the touch surface.
 26. The computingdevice of claim 25, wherein the touch surface is a touchscreen display.27. The computing device of claim 25, further comprising: means forinitiating a rapid pan or scroll animation if the touch event representsa flick gesture; means for determining whether an end of the rapid panor scroll animation has been reached; and means for animating thedistortion of the image displayed on the computing device if theboundary of the image displayed on the computing device is reachedbefore the end of the rapid pan or scroll animation is reached.
 28. Thecomputing device of claim 27, wherein means for animating the distortionof the image displayed on the computing device comprises means foranimating a bouncing movement of the image displayed on the computingdevice.
 29. The computing device of claim 27, wherein means foranimating the distortion of the image displayed on the computing devicecomprises means for animating a bouncing movement and a compressiondistortion of the image displayed on the computing device.
 30. Thecomputing device of claim 21, further comprising: means for determiningwhether a maximum level of display image distortion is reached; andmeans for reverting the image displayed on the computing device back toits original form if the maximum level of display image distortion isreached.
 31. A non-transitory processor-readable storage medium havingstored thereon processor-executable instructions configured to cause acomputer device processor to perform operations, comprising: detectingan image movement gesture input on a user interface device of acomputing device; determining an image movement of an image displayed onthe computing device based on the detected image movement gesture input;determining whether a boundary of the image displayed on the computingdevice is reached based on the determined image movement; determining adistortion function to be applied to distort the image displayed on thecomputing device; calculating a distortion factor based on a distancethe image movement gesture input would move the image displayed on thecomputing device after the boundary of the image displayed on thecomputing device is reached; and distorting the image displayed on thecomputing device when a boundary of the image is reached by applying thedetermined distortion function to the image displayed on the computingdevice based on the calculated distortion factor.
 32. The non-transitoryprocessor-readable storage medium of claim 31, wherein the storedprocessor-executable instructions are configured to cause a computerdevice processor to perform operations such that distorting the imagedisplayed on the computing device comprises one of stretching the imagedisplayed on the computing device, shrinking the image displayed on thecomputing device, and bouncing the image displayed on the computingdevice.
 33. The non-transitory processor-readable storage medium ofclaim 31, wherein the stored processor-executable instructions areconfigured to cause a computer device processor to perform operationssuch that distorting the image displayed on the computing deviceincludes distorting the image displayed on the computing device along anaxis selected from a horizontal axis, a vertical axis, a diagonal axis,and both the horizontal and vertical axes.
 34. The non-transitoryprocessor-readable storage medium of claim 31, wherein the storedprocessor-executable instructions are configured to cause a computerdevice processor to perform operations such that distorting the imagedisplayed on the computing device includes distorting the imagedisplayed on the computing device in an accordion style by insertingspace between elements of the image displayed on the computing devicewithout distorting the elements the image displayed on the computingdevice.
 35. The non-transitory processor-readable storage medium ofclaim 31, wherein the stored processor-executable instructions areconfigured to cause a computer device processor to perform operationssuch that: the user interface device is a touch surface; and the imagemovement gesture input is a touch event detected on the touch surface.36. The non-transitory processor-readable storage medium of claim 35,wherein the stored processor-executable instructions are configured tocause a computer device processor to perform operations such that thetouch surface is a touchscreen display.
 37. The non-transitoryprocessor-readable storage medium of claim 35, wherein the storedprocessor-executable instructions are configured to cause a computerdevice processor to perform operations further comprising: initiating arapid pan or scroll animation if the touch event represents a flickgesture; determining whether an end of the rapid pan or scroll animationhas been reached; and animating the distortion of the image displayed onthe computing device if the boundary of the image displayed on thecomputing device is reached before the end of the rapid pan or scrollanimation is reached.
 38. The non-transitory processor-readable storagemedium of claim 37, wherein the stored processor-executable instructionsare configured to cause a computer device processor to performoperations such that animating the distortion of the image displayed onthe computing device comprises animating a bouncing movement of theimage displayed on the computing device.
 39. The non-transitoryprocessor-readable storage medium of claim 37, wherein the storedprocessor-executable instructions are configured to cause a computerdevice processor to perform operations such that animating thedistortion of the image displayed on the computing device comprisesanimating a bouncing movement and a compression distortion of the imagedisplayed on the computing device.
 40. The non-transitoryprocessor-readable storage medium of claim 31, wherein the storedprocessor-executable instructions are configured to cause a computerdevice processor to perform operations further comprising: determiningwhether a maximum level of display image distortion is reached; andreverting the image displayed on the computing device back to itsoriginal form if the maximum level of display image distortion isreached.
 41. A method for implementing a user interface function on acomputing device, comprising: detecting an image movement gesture inputon a user interface device of the computing device; determining an imagemovement of an image displayed on the computing device based on thedetected image movement gesture input; determining whether a boundary ofthe image displayed on the computing device is reached based on thedetermined image movement; and distorting the image displayed on thecomputing device when a boundary of the image is reached, whereindistorting the image displayed on the computing device includesdistorting the image displayed on the computing device in an accordionstyle by inserting space between elements of the image displayed on thecomputing device without distorting the elements of the image displayedon the computing device.
 42. A computing device, comprising: aprocessor; a display coupled to the processor; and a user interfacedevice coupled to the processor, wherein the processor is configuredwith processor-executable instructions to perform operations comprising:detecting an image movement gesture input on the user interface deviceof the computing device; determining an image movement of an imagedisplayed on the display based on the detected image movement gestureinput; determining whether a boundary of the image displayed on thedisplay is reached based on the determined image movement; anddistorting the image displayed on the display when a boundary of theimage is reached such that distorting the image displayed on the displayincludes distorting the image displayed on the display in an accordionstyle by inserting space between elements of the image displayed on thedisplay without distorting the elements of the image displayed on thedisplay.
 43. A computing device, comprising: means for detecting animage movement gesture input on a user interface device of the computingdevice; means for determining an image movement of an image displayed onthe computing device based on the detected image movement gesture input;means for determining whether a boundary of the image displayed on thecomputing device is reached based on the determined image movement; andmeans for distorting the image displayed on the computing device when aboundary of the image is reached by distorting the image displayed onthe computing device in an accordion style by inserting space betweenelements of the image displayed on the computing device withoutdistorting the elements of the image displayed on the computing device.44. A non-transitory processor-readable storage medium having storedthereon processor-executable instructions configured to cause acomputing device processor to perform operations, comprising: detectingan image movement gesture input on a user interface device of thecomputing device; determining an image movement of an image displayed onthe computing device based on the detected image movement gesture input;determining whether a boundary of the image displayed on the computingdevice is reached based on the determined image movement; and distortingthe image displayed on the computing device when a boundary of the imageis reached such that distorting the image displayed on the computingdevice includes distorting the image displayed on the computing devicein an accordion style by inserting space between elements of the imagedisplayed on the computing device without distorting the elements of theimage displayed on the computing device.